Pacific salmon welfare in the open ocean is influenced by prey availability, predation, and ocean conditions that are changing rapidly with climate and fishing pressure.
Open-ocean salmon welfare is less visible than the dramatic struggles of upstream migration but equally important for overall welfare across the life cycle. Salmon in poor ocean condition arrive at river mouths depleted, facing an exhausting migration with inadequate reserves. Starvation stress during periods of low ocean productivity reduces immune function and increases disease susceptibility. Ocean conditions that support abundant prey are fundamental to salmon welfare and are declining in many regions due to warming and acidification.